This invention relates generally to the field of subterranean horizontal and directional drilling, and more particularly, but not by way of limitation, to a transmitter housing for supporting a transmitting probe or sonde used to steer and direct a drilling apparatus.
Recent advances in directional underground drilling offers significant advantages over earlier methods in a number of applications. Underground directional drilling eliminates the need for trenching and backfilling in laying pipeline and other utilities. Underground directional drilling furthermore provides greater flexibility and increased opportunities for subterranean drilling, such as in the drilling for subterranean fluids and in core sampling.
Many differing approaches have been undertaken in the development of underground directional drilling. Generally, a cutting tool is advanced at a distal end of a drill string. A drilling fluid, such as water, is flowed through the drill string, over the cutting tool, and back up the bore hole in order to remove cuttings and debris as the bore is created. A transmitting probe typically is employed in the drill string near the cutting tool in order to monitor the location of the cutting tool, and to steer and direct the cutting tool.
The type of transmitting probe employed varies, depending on the nature of the boring environment and the relative boring accuracy needed. U.S. Pat. No. 4,787,463 issued to Geller, for example, teaches the use of an active beam radio transmitter in conjunction with a tracking receiver above ground. Alternatively, U.S. Pat. No. 5,720,354 issued to Stump teaches a ground penetrating radar unit wherein the transmitter generates a specific signature signal in response to a probe signal from the radar unit above ground.
The type of cutting action employed also varies. U.S. Pat. No. 4,144,941 issued to Ritter teaches the widely used impact method for directional tunneling. Numerous improvements to this early teaching have been made in the art, such as provided in the hammering method of directional drilling wherein the cutting head is not rotated, such as is taught in U.S. Pat. No. 4,694,913 issued to McDonald, and U.S. Pat. No. 5,109,932 issued to Breter.
Where these general advancements in the art generally require the support of a transmitter near the impact-cutting head of the drilling apparatus, such a requirement presents challenging difficulties. The rotational and axial position of the transmitter must be provided for and maintained, without damaging the relatively delicate transmitter. Conventional fasteners, also, have demonstrated the propensity to vibrate loose during the repeated impact cycles of hammering, resulting in erroneous readings, as well as lost and damaged transmitters.
There is a need in the industry for a transmitter housing that is disposable in the drill string and that, in turn, receivingly supports a conventional transmitting probe in a reliable manner, not relying on conventional fasteners such as threaded screws to support or enclose the transmitting probe.
The present invention provides a transmitter housing for the containment of a probe in a directional underground drilling device, the transmitter housing having a housing with first and second ends and a longitudinally extending bore for receiving the probe, the housing having a first detent near the first end. A cover member is slidingly engaged by the first by the first detent to cover the bore and to secure the probe in the housing. A sub member engages the second end of the housing to secure the cover member on the housing.
A positioning member is disposed in the bore and engages the probe for rotationally positioning the probe in a desired orientation in the bore of the housing. Preferably, the housing has a plurality of slots or the like for selectively orienting the probe.
The housing has a passageway for fluid flow, and has a plurality of slots to permit the signal transmission.
The objects, features and advantages of the present invention will be clear upon reading the description provided together with the drawings and appended claims.